Generally, a method of fabricating an integrated circuit device (hereinafter, referred to as IC) or an LSI device includes a wafer testing process for testing IC chips formed in a wafer to determine whether or not the IC chips are acceptable. In the wafer testing process, in general, a probe card is mounted on a device called a prober, and a probe included in the probe card are brought into contact with predetermined pads (electrodes) formed on the chips of the wafer. More specifically, electrical connection of the prober and the pad is achieved by applying a predetermined pressure (hereinafter referred to as "needle pressure") to the probe after the probe has been brought into contact with the pad for overdriving so that the probe penetrates an aluminum oxide film forming the surface of the pad and comes into low-resistance contact with an aluminum portion forming the body of the pad.
When the needle pressure is applied to the probe to bring the probe into contact with the aluminum portion of the pad, foreign matters including aluminum oxide chips adhering to the chip and the probe obstruct the electrical connection. Various measures have been taken to prevent problems in achieving the electrical contact.
The probe for the electrical testing of a semiconductor wafer is cleaned periodically by using an abrading pad or an abrasive sheet to remove foreign materials which are scraped off of the pads of ICs and adhere to an end portion of the probe. Abrasive pads composed of a mixture of an elastic base material and abrasive particles are disclosed in JP-A No. 7-244074 (Registration No. 2511806) and JP-A No. 56-119377. Foreign materials adhering to the end portion of the probe are scraped off the end portion by repeating a cleaning cycle of sticking or pressing and extracting the end portion of the probe against a probe cleaning tool to maintain the end portion of the probe in a good shape.
FIG. 6 is an enlarged sectional view illustrating the interaction between an end portion 20 of a probe, an abrasive pad 40 and foreign material adhering to the end portion 20. The end portion 20 of the probe consists of a substantially spherical round tip 21 and a conical section 22 smoothly merging into the round tip 21.
In FIG. 6, al indicates the condition of the end portion 20 before being subjected to a cleaning operation in which the sticking-and-extracting cleaning cycle is repeated, a2 indicates the condition of the end portion 20 as it is stuck into the abrasive pad 40, and a3 indicates the condition of the end portion 20 after it has it has been extracted from the abrasive pad 40 after the completion of the cleaning operation.
The abrasive pad 40 shown in FIG. 6 is formed by mixing an elastic base material 41 and abrasive particles 42 (abrasive grains). There are some cases where the base material 41 and the abrasive particles 42 are worn and fall off the abrasive pad 40 to produce additional foreign material when the sticking-and-extracting cleaning cycle is repeated.
The condition of foreign material adhering to the end portion 20 of the probe in the states al, a2 and a3 will be explained. FIG. 6 depicts primary foreign material 101 such as aluminum oxide chips, adhering to the end portion 20 of the probe during the wafer testing process, and secondary foreign material 102, such as particles of silicone rubber and abrasive grains, produced during the cleaning process.
In the state a3 after the completion of a cleaning operation in which the sticking-and-extracting cleaning cycle is repeated, the foreign materials 101 and 102 have been removed from the round tip 21 of the end portion 20 of the probe, and the foreign materials 101 and 102 once removed from the end portion 20 have adhered again to the conical section 22 of the end portion 20 of the probe. All the foreign materials 101 and 102 adhering to the conical section 22 of the end portion 20 can be removed to complete the cleaning operation by blowing an organic solvent against the end portion 20 of the probe and blowing dry air against the end portion 20 of the probe.
When carrying out the conventional probe cleaning method by using the conventional abrasive pad 40, a problem arises when extracting the end portion 20 of the probe stuck into the abrasive pad 40 from the abrasive pad 40. When the end portion 20 of the probe is extracted from the abrasive pad 40, chips of the pads of the IC once scraped off the end portion 20 of the probe adhere again to the end portion 20, and secondary foreign material, such as particles produced from the worn base material 41 and the abrasive particles 42 of the abrasive pad 40, adhere to the end portion 20 of the probe. Therefore, an additional cleaning operation using an organic solvent is necessary to clean the end portion 20 perfectly.